(nicotinamide adenine dinucleotide) a *coenzyme that acts as a hydrogen acceptor in oxidation-reduction reactions, particularly in the *electron transport chain in cellular respiration. NAD and the closely related coenzyme NADP (nicotinamide adenine dinucleotide phosphate) are derived from nicotinic acid; they are reduced to NADH and NADPH, respectively.... nad
(niacin) a B vitamin. Nicotinic acid is a derivative of pyridine and is interchangeable with its amide, nicotinamide. Both forms of the vitamin are equally active. Nicotinamide is a component of the coenzymes *NAD (nicotinamide adenine dinucleotide) and NADP, its phosphate. Nicotinic acid is required in the diet, but can also be synthesized from the essential amino acid tryptophan. A deficiency of the vitamin leads to *pellagra. Good sources of nicotinic acid are meat, yeast extracts, and pulses. The adult RNI (see Dietary Reference Values) depends on the kcal content of the diet and is 6.6 mg niacin equivalent/1000 kcal, which equates to about 17 mg/day for males and 13 mg/day for females. 1 mg niacin equivalent is equal to 1 mg of available nicotinic acid or 60 mg tryptophan.... nicotinic acid
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